/* *  Copyright (c) 2010 The WebM project authors. All Rights Reserved. * *  Use of this source code is governed by a BSD-style license *  that can be found in the LICENSE file in the root of the source *  tree. An additional intellectual property rights grant can be found *  in the file PATENTS.  All contributing project authors may *  be found in the AUTHORS file in the root of the source tree. */ #include "dboolhuff.h"#include "vp8/common/common.h"#include "vpx_dsp/vpx_dsp_common.h" int vp8dx_start_decode(BOOL_DECODER *br, const unsigned char *source,                       unsigned int source_sz, vpx_decrypt_cb decrypt_cb,                       void *decrypt_state) {  if (source_sz && !source) return 1;   // To simplify calling code this fuction can be called with |source| == null  // and |source_sz| == 0. This and vp8dx_bool_decoder_fill() are essentially  // no-ops in this case.  // Work around a ubsan warning with a ternary to avoid adding 0 to null.  br->user_buffer_end = source ? source + source_sz : source;  br->user_buffer = source;  br->value = 0;  br->count = -8;  br->range = 255;  br->decrypt_cb = decrypt_cb;  br->decrypt_state = decrypt_state;   /* Populate the buffer */  vp8dx_bool_decoder_fill(br);   return 0;} void vp8dx_bool_decoder_fill(BOOL_DECODER *br) {  const unsigned char *bufptr = br->user_buffer;  VP8_BD_VALUE value = br->value;  int count = br->count;  int shift = VP8_BD_VALUE_SIZE - CHAR_BIT - (count + CHAR_BIT);  size_t bytes_left = br->user_buffer_end - bufptr;  size_t bits_left = bytes_left * CHAR_BIT;  int x = shift + CHAR_BIT - (int)bits_left;  int loop_end = 0;  unsigned char decrypted[sizeof(VP8_BD_VALUE) + 1];   if (br->decrypt_cb) {    size_t n = VPXMIN(sizeof(decrypted), bytes_left);    br->decrypt_cb(br->decrypt_state, bufptr, decrypted, (int)n);    bufptr = decrypted;  }   if (x >= 0) {    count += VP8_LOTS_OF_BITS;    loop_end = x;  }   if (x < 0 || bits_left) {    while (shift >= loop_end) {      count += CHAR_BIT;      value |= (VP8_BD_VALUE)*bufptr << shift;      ++bufptr;      ++br->user_buffer;      shift -= CHAR_BIT;    }  }   br->value = value;  br->count = count;}